U.S. patent application number 14/458819 was filed with the patent office on 2014-11-27 for fabricating method of electrode assembly and electrochemical cell containing the same.
The applicant listed for this patent is LG CHEM. LTD.. Invention is credited to Jin Ho BAN, Myung Hoon KO, Hyang Mok LEE, Ji Won PARK, Seung Jae YOU.
Application Number | 20140349192 14/458819 |
Document ID | / |
Family ID | 49624109 |
Filed Date | 2014-11-27 |
United States Patent
Application |
20140349192 |
Kind Code |
A1 |
PARK; Ji Won ; et
al. |
November 27, 2014 |
FABRICATING METHOD OF ELECTRODE ASSEMBLY AND ELECTROCHEMICAL CELL
CONTAINING THE SAME
Abstract
A fabricating method of an electrode assembly according to the
present invention includes forming a radical unit having a
four-layered structure obtained by stacking a first electrode, a
first separator, a second electrode, and a second separator one by
one, and stacking at least one radical unit one by one to form a
unit stack part.
Inventors: |
PARK; Ji Won; (Daejeon,
KR) ; YOU; Seung Jae; (Daejeon, KR) ; KO;
Myung Hoon; (Daejeon, KR) ; BAN; Jin Ho;
(Daejeon, KR) ; LEE; Hyang Mok; (Daejeon,
KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
LG CHEM. LTD. |
Seoul |
|
KR |
|
|
Family ID: |
49624109 |
Appl. No.: |
14/458819 |
Filed: |
August 13, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
PCT/KR2013/004526 |
May 23, 2013 |
|
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|
14458819 |
|
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Current U.S.
Class: |
429/246 ;
29/623.1; 29/623.5 |
Current CPC
Class: |
H01M 2/1646 20130101;
H01G 11/12 20130101; H01G 11/86 20130101; H01M 10/0413 20130101;
H01M 2/1673 20130101; H01M 10/0468 20130101; H01M 10/0445 20130101;
H01M 4/04 20130101; H01M 10/0525 20130101; Y10T 29/49108 20150115;
H01M 2/168 20130101; Y10T 29/49115 20150115; H01M 10/0583 20130101;
Y02E 60/10 20130101; H01M 2/145 20130101; Y02E 60/13 20130101; Y02T
10/70 20130101; H01M 4/0404 20130101 |
Class at
Publication: |
429/246 ;
29/623.1; 29/623.5 |
International
Class: |
H01M 4/04 20060101
H01M004/04; H01M 2/16 20060101 H01M002/16; H01M 2/14 20060101
H01M002/14 |
Foreign Application Data
Date |
Code |
Application Number |
May 23, 2012 |
KR |
10-2012-0055074 |
May 23, 2013 |
KR |
10-2013-0058165 |
Claims
1. A fabricating method of an electrode assembly comprising:
forming a radical unit having a four-layered structure obtained by
stacking a first electrode, a first separator, a second electrode,
and a second separator one by one; and stacking at least one
radical unit one by one to form a unit stack part.
2. The fabricating method of an electrode assembly of claim 1,
wherein the radical unit is formed by attaching the electrode and
the separator to each other.
3. The fabricating method of an electrode assembly of claim 2,
wherein an attachment of the electrode and the separator is
conducted by pressurizing the electrode and the separator, or by
applying pressure and heat onto the electrode and the
separator.
4. The fabricating method of an electrode assembly of claim 2,
wherein the separator is coated with a coating material having
adhesiveness.
5. The fabricating method of an electrode assembly of claim 4,
wherein the coating material is a mixture of inorganic particles
and a binder polymer.
6. The fabricating method of an electrode assembly of claim 4,
wherein both sides of the first separator facing the first
electrode and the second electrode are coated with the coating
material, and one side of the second separator facing the second
electrode is coated with the coating material.
7. The fabricating method of an electrode assembly of claim 4,
wherein both sides of the first separator facing the first
electrode and the second electrode are coated with the coating
material, and one side of the second separator facing the second
electrode and an opposite side thereof are coated with the coating
material, the unit stack part being obtained by stacking at least
two radical units, the radical units being attached to each other
through the coating material of the second separator.
8. The fabricating method of an electrode assembly of claim 1,
wherein the radical unit is obtained by repeatedly stacking the
four-layered structures.
9. The fabricating method of an electrode assembly of claim 1,
further comprising stacking of first auxiliary unit on a first
distal end electrode, the first distal end electrode being the
first electrode positioned at an uppermost or a lowermost portion
of the unit stack part, when the first electrode being an cathode,
and the second electrode being a anode, the first auxiliary unit
being formed by stacking from the first distal end electrode, the
separator, the anode, the separator and the cathode one by one,
when the first electrode being the anode, and the second electrode
being the cathode, the first auxiliary unit being formed by
stacking from the first distal end electrode, the separator and the
cathode one by one.
10. The fabricating method of an electrode assembly of claim 9,
wherein the cathode of the first auxiliary unit comprises: a
current collector; and an active material coated only on one side
facing the radical unit among both sides of the current
collector.
11. The fabricating method of an electrode assembly of claim 1,
further comprising stacking a first auxiliary unit on a first
distal end electrode, the first distal end electrode being the
first electrode positioned at an uppermost or a lowermost portion
of the unit stack part, when the first electrode being an cathode,
and the second electrode being a anode, the first auxiliary unit
being formed by stacking from the first distal end electrode, the
separator, the anode, and the separator one by one.
12. The fabricating method of an electrode assembly of claim 1,
wherein the unit stack part further comprises a second auxiliary
unit stacked on a second distal end separator, the second distal
end separator being the second separator positioned at an uppermost
or a lowermost portion of the unit stack part, when the first
electrode being an cathode, and the second electrode being a anode,
the second auxiliary unit being formed by stacking from the second
distal end separator, the anode, the separator and the cathode one
by one.
13. The fabricating method of an electrode assembly of claim 12,
wherein the cathode of the secondary auxiliary unit comprises: a
current collector; and an active material coated only on one side
facing the radical unit among both sides of the current
collector.
14. The fabricating method of an electrode assembly of claim 1,
further comprising stacking a second auxiliary unit on a second
distal end separator, the second distal end separator being the
second separator positioned at an uppermost or a lowermost portion
of the unit stack part, when the first electrode being an cathode,
and the second electrode being a anode, the second auxiliary unit
being formed by stacking from the second distal end separator, the
first cathode, the separator, the anode, the separator and the
second cathode one by one, the second cathode of the secondary
auxiliary unit comprising a current collector and an active
material coated only on one side facing the radical unit among both
sides of the current collector.
15. The fabricating method of an electrode assembly of claim 1,
further comprising stacking a second auxiliary unit on a second
distal end separator, the second distal end separator being the
second separator positioned at an uppermost or a lowermost portion
of the unit stack part, when the first electrode being a anode, and
the second electrode being an cathode, the second auxiliary unit
being formed by stacking from the second distal end separator, the
anode, the separator, the cathode, the separator and the anode, one
by one.
16. The fabricating method of an electrode assembly of claim 1,
further comprising fixing by using a polymer tape for taping the
side portion or the front portion of the unit stack part.
17. An electrochemical device comprising the electrode assembly
obtained by the fabricating method according to claim 1.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a fabricating method of an
electrode assembly manufactured by a stacking method other than a
folding method, and an electrochemical cell containing the
same.
BACKGROUND OF THE ART
[0002] This application claims the priority of Korean Patent
Application No. 10-2012-0055074 filed on May 23, 2012, and Korean
Patent Application No.10-2013-0058165 filed on May 23, 2013, in the
Korean Intellectual Property Office, the disclosure of which is
incorporated herein by reference.
[0003] A secondary battery attracts attention as a power source of
an electric vehicle (EV), a hybrid electric vehicle (HEV), a
parallel hybrid electric vehicle (PHEV), and the like, which have
been suggested as alternatives for solving defects such as
environmental contamination due to commonly used gasoline vehicles,
diesel vehicles, and the like using fossil fuels. In a medium and
large size device such as automobiles, a medium and large size
battery module in which a plurality of battery cells is
electrically connected is used due to the need of high power and
high capacity.
[0004] However, since the medium and large size battery module is
necessary to be manufactured so as to have a small size and a light
weight, a square shape battery, a pouch shape battery, etc., which
may be stacked in a high degree and have a light weight when
compared with the capacity, are widely used as the battery cells of
the medium and large size battery module.
[0005] Generally, an electrode assembly may be classified according
to the structure of the electrode assembly having
cathode/separator/anode. Typically, the electrode assembly may be
classified into a jelly-roll (a wrapping type) electrode assembly,
in which cathodes and anodes having long sheet shapes along with an
interposed separator are wrapped, a stack type (a laminated type)
electrode assembly, in which a plurality of cathodes and anodes
along with interposed separators, which are cut into specific size
units and stacked one by one, and a stack/folding type electrode
assembly. The stack/folding type and the stack type electrode
assemblies are typically used, and defects on each structure will
be explained.
[0006] First, the stack/folding type electrode assembly disclosed
in Korean Patent Application Publication Nos. 2001-0082058,
2001-0082059 and 2001-0082060 filed by the present Applicant will
be explained.
[0007] Referring to FIG. 13, an electrode assembly 1 of a
stack/folding structure includes a plurality of overlapped full
cells 2, 3, 4 . . . (Hereinafter, will be referred to as `full
cell`) as a unit cells, in which cathode/separator/anode are
positioned in sequence. In each of the overlapped parts, a
separator sheet 5 is interposed. The separator sheet 5 has a unit
length possibly wrapping the full cells. The separator sheet 5
initiated from the central full cell 10 is bent inward by the unit
length while continuously wrapping each of the full cells to the
outermost full cell 14 so as to be interposed in the overlapped
parts of the full cells. The distal end portion of the separator
sheet 5 is finished by conducting heat welding or attaching using
an adhesion tape 6. The stack/folding type electrode assembly is
manufactured by, for example, arranging the full cells 2, 3, 4 . .
. on the separator sheet 5 having a long length and wrapping from
one end portion of the separator sheet 5 in sequence. However, in
this structure, a temperature gradient may be generated between the
electrode assemblies 1a, 1b and 2 in the center portion and the
electrode assemblies 3 and 4 disposed at the outer portion to
produce different heat emitting efficiency. Thus, the lifetime of
the electrode assembly may be decreased when used for a long
time.
[0008] The manufacturing process of the electrode assembly is
conducted by using two lamination apparatuses for manufacturing
each electrode assembly and one additional folding apparatus as a
separate apparatus. Therefore, the decrease of the tack time of the
manufacturing process has a limitation. Particularly, the minute
aligning of the electrode assemblies disposed up and down is
difficult in the structure accomplishing the stacked structure
through the folding. Thus, the manufacture of an assembly having a
reliable quality is very difficult.
[0009] FIG. 14 illustrates the structures of A type and C type
bicells different from the full cell structure as a unit cell
applicable in the above-described folding structure in FIG. 13. At
the center portion which is an initiating point of wrapping among
the overlapped electrochemical cells applicable in the present
invention, a bicell having a
cathode/separator/anode/separator/cathode structure (a) (A type
bicell), or a bicell having a
anode/separator/cathode/separator/anode structure (b) (C type
bicell), surrounded by a separator sheet is disposed. That is, the
structure of a common bicell may be accomplished by `A type bicell`
having a stacked structure of a double sided cathode 10, a
separator 20, a double sided anode 30, a separator 40, a double
sided cathode 50 one by one as illustrated in FIG. 14 (a), or a
stacked structure of a double sided anode 30, a separator 20, a
double sided cathode 10, a separator 40, and a double sided anode
50 one by one as illustrated in FIG. 14 (b).
[0010] For the structure of the electrode assembly using the
folding process, a folding apparatus is separately necessary. When
a bicell structure is applied, two types of the bicells of the A
type and the C type, are manufactured and stacked. Before
conducting the folding, the keeping of the distance between one
bicell and another bicell disposed on a long separator sheet is a
very difficult task. That is, an accurate alignment between the
upper and lower unit cells may be difficult. When manufacturing a
high capacity cell, a considerable time may be necessary for
changing the types.
[0011] Next, a stack type electrode assembly will be explained.
Since the stack type electrode assembly is widely known in this
art, only on the defects of the stack type electrode assembly will
be explained in brief.
[0012] Generally, in the stack type electrode assembly, the length
and the width of a separator are greater than those of an
electrode. The separator is stacked on a magazine or a jig having
corresponding size with respect to the length and the width of the
separator, and the stacking process of the electrode on the
separator is repeatedly conducted to manufacture the stack type
electrode assembly.
[0013] However, when the stack type electrode assembly is
manufactured by the above-described method, the electrode and the
separator are necessary to be stacked one by one. Thus, the working
time is increased to remarkably lower the productivity. In
addition, the alignment of the plurality of the separators by the
length and the width is possible. However, since the magazine or
the jig accurately aligning the electrodes put on the separator is
not present, the plurality of the electrodes provided in the stack
type electrode assembly may not be aligned but may be
dislocated.
[0014] In addition, since the faces of the cathode and the anode
across the separator are dislocated, an electrochemical reaction
may not be made in a portion of the active material region coated
on the surfaces of the cathode and the anode. Thus, the efficiency
of a battery cell may be deteriorated.
SUMMARY OF THE INVENTION
[0015] An aspect of the present invention considering the
above-described defects, provides a fabricating method
accomplishing the maximization of simplifying a process and a cost
reduction by manufacturing a unit cell having a radical unit
structure, deviated from the unit cell of the A or C type bicell
structure, which is applicable in the folding process, and by
manufacturing a secondary battery through conducting only a
stacking process other than a folding process.
[0016] According to an aspect of the present invention, there is
provided a fabricating method of an electrode assembly including
forming a radical unit having a four-layered structure obtained by
stacking a first electrode, a first separator, a second electrode,
and a second separator one by one, and stacking at least one
radical unit one by one to form a unit stack part.
[0017] Further, the method may further include a step of stacking a
first auxiliary unit on a first distal end electrode which is the
first electrode positioned at the uppermost or the lowermost
portion of the unit stack part, and a step of stacking a second
auxiliary unit on a second distal end electrode which is the second
electrode positioned at the uppermost or the lowermost portion of
the unit stack part.
[0018] In addition, the method may further include a step of fixing
by taping the side portion or the front portion of the unit stack
part by using a polymer tape.
EFFECT OF THE INVENTION
[0019] According to the fabricating method of an electrode assembly
of the present invention, radical units may be minutely aligned and
the productivity may be increased.
[0020] In addition, according to the fabricating method of an
electrode assembly of the present invention, a coating material is
coated only on one side of a second separator facing a second
electrode, and a cost reduction effect may be large.
[0021] In addition, according to the fabricating method of an
electrode assembly of the present invention, only a step of
stacking a first auxiliary unit and a second auxiliary unit
including only one coated layer of an active material layer at the
outermost portion on a unit stack part is included, and the waste
of the active material layer may be prevented.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] The above and other aspects, features and other advantages
of the present invention will be more clearly understood from the
following detailed description taken in conjunction with the
accompanying drawings, in which:
[0023] FIG. 1 is a side view illustrating a first structure of a
radical unit according to the present invention;
[0024] FIG. 2 is a side view of a second structure of a radical
unit according to the present invention;
[0025] FIG. 3 illustrates a process for manufacturing a radical
unit according to the present invention;
[0026] FIG. 4 is a side view illustrating a first structure of a
unit stack part including a radical unit and a first auxiliary unit
according to the present invention;
[0027] FIG. 5 is a side view illustrating a second structure of a
unit stack part including a radical unit and a first auxiliary unit
according to the present invention;
[0028] FIG. 6 is a side view illustrating a third structure of a
unit stack part including a radical unit and a second auxiliary
unit according to the present invention;
[0029] FIG. 7 is a side view illustrating a fourth structure of a
unit stack part including a radical unit and a second auxiliary
unit according to the present invention;
[0030] FIG. 8 is a side view illustrating a fifth structure of a
unit stack part including a radical unit, a first auxiliary unit
and a second auxiliary unit according to the present invention;
[0031] FIG. 9 is a side view illustrating a sixth structure of a
unit stack part including a radical unit and a first auxiliary unit
according to the present invention;
[0032] FIG. 10 is a side view illustrating a seventh structure of a
unit stack part including a radical unit and a second auxiliary
unit according to the present invention;
[0033] FIG. 11 is a flow chart illustrating a fabricating method of
an electrode assembly according to the present invention;
[0034] FIG. 12 is a conceptual diagram illustrating a fixing part
of an electrode assembly according to the present invention;
[0035] FIG. 13 is a conceptual diagram illustrating a folding
structure of an electrode assembly according to related arts;
and
[0036] FIG. 14 is a side view illustrating A type and C type bicell
structures applicable in the folding structure in FIG. 13.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0037] Exemplary embodiments of the present invention will now be
described in detail with reference to the accompanying drawings.
However, the present invention is not restricted or limited to the
following exemplary embodiments.
[0038] A unit stack part (see 100a in FIG. 4) includes at least one
radical unit (see 110a in FIG. 1, etc.). That is, a unit stack part
100 includes one radical unit 110 or at least two radical units 110
. The unit stack part 100 is formed by stacking the radical units
110. For example, the unit stack part 100 may be formed by stacking
one radical unit 110 on another radical unit 110. As
described-above, the unit stack part 100 is formed by stacking the
radical units 110 as a unit. That is, the radical units 110 are
previously formed and then stacked one by one to form the unit
stack part 100.
[0039] As described above, the unit stack part 100 in accordance
with this example embodiment has basic features in repeatedly
stacking the radical units 110 for the manufacture thereof. Through
manufacturing the unit stack part 100 by the above-described
method, merits may be obtained, that the radical unit 110 may be
minutely aligned, and the productivity may be improved.
[0040] The radical unit 110 is formed by stacking a first electrode
111, a first separator 112, a second electrode 113 and a second
separator 114 one by one. As described above, the radical unit 110
basically includes a four-layered structure. More particularly, the
radical unit 110 may be formed by stacking the first electrode 111,
the first separator 112, the second electrode 113 and the second
separator 114 one by one from the upper portion to the lower
portion as illustrated in FIG. 1, or may be formed by stacking the
first electrode 111, the first separator 112, the second electrode
113 and the second separator 114 one by one from the lower portion
to the upper portion as illustrated in FIG. 2. In this case, the
first electrode 111 and the second electrode 113 have opposite
electrodes to each other. For example, when the first electrode 111
is an cathode, the second electrode 113 is an anode. Of course, the
reverse case may be possible.
[0041] The radical unit 110 may be formed by the following process
(see FIG. 3). First, a first electrode material 121, a first
separator material 122, a second electrode material 123 and a
second separator material 124 are prepared. In this case, the
electrode materials 121 and 123 are cut into a certain size to form
the electrodes 111 and 113, which will be described herein below.
Similarly, the separator materials 122 and 124 are cut into a
certain size. For process automation, the electrode materials and
the separator materials may preferably have a wrapped shape on a
roll. After preparing the materials, the first electrode material
121 is cut into the certain size by means of a cutter C.sub.1.
Then, the second electrode material 123 also is cut into the
certain size by means of a cutter C.sub.2. Then, the first
electrode material 121 having the certain size is supplied on the
first separator material 122. The second electrode material 123
having the certain size also is supplied on the second separator
material 124. Then, all of the materials are supplied to laminators
L.sub.1 and L.sub.2.
[0042] As described above, the unit stack part 100 is formed by
repeatedly stacking the radical units 110. However, when the
electrode and the separator constituting the radical unit 110 are
separated from each other, the repeated stacking of the radical
units 110 may be very difficult. Thus, the electrode and the
separator may be preferably attached to each other when forming the
radical units 110. The laminators L.sub.1 and L.sub.2 are used for
attaching the electrode and the separator to each other. That is,
the laminators L.sub.1 and L.sub.2 apply a pressure, or heat and
pressure to the materials to accomplish the attachment of the
electrode material and the separator material. The electrode
material and the separator material are attached to each other by
means of the laminators L.sub.1 and L.sub.2. Through the
attachment, the radical units 110 may maintain the shape itself
more stably.
[0043] Finally, both of the first separator material 122 and the
second separator material 124 are cut into a certain size by using
a cutter C.sub.3. Through the cutting, the radical units 110 may be
formed. Various kinds of inspections may be additionally conducted
with respect to the radical units 110. For example, inspections on
thickness, vision, short, or the like may be additionally
conducted.
[0044] Meanwhile, the surface of the separator (separator material)
may be coated with a coating material having adhesiveness. In this
case, the coating material may be a mixture of inorganic particles
and a binder polymer. The inorganic particles may improve the
thermal stability of the separator. That is, the inorganic
particles may prevent the contraction of the separator at a high
temperature. In addition, the binder polymer may fix the inorganic
particles. Thus, the inorganic particles may include certain pore
structures. Due to the pore structure, ions may smoothly move from
the cathode to the anode, even though the inorganic particles are
coated on the separator. In addition, the binder polymer may keep
the inorganic particles stably on the separator to improve the
mechanical stability of the separator. Further, the binder polymer
may attach the separator onto the electrode more stably. For
reference, the separator may be formed by using a polyolefin-based
separator substrate.
[0045] However, as illustrated in FIGS. 1 and 2, at both sides of
the first separator 112, the electrodes 111 and 113 are positioned.
However, only one electrode 113 is positioned at one side of the
second separator 114. Thus, the coating material may be coated on
both sides of the first separator 112, while the coating material
may be coated on one side of the second separator 114. That is,
both sides of the first separator 112 facing the first electrode
111 and the second electrode 113 may be coated with the coating
material, and one side of the second separator 114 facing the
second electrode 113 may be coated with the coating material.
[0046] As described above, the attachment by using the coating
material may be sufficient when accomplished within the radical
unit . Thus, the coating may be conducted with respect to only one
side of the second separator 114 as described above. Merely, since
adhesion among the radical units may be accomplished by applying a
method such as heat press, both sides of the second separator 114
may be coated as occasion demands. That is, the coating material
may be coated on one side of the second separator 114 facing the
second electrode 113 and on the opposite side thereof. In this
case, the radical unit positioned at the upper portion and the
radical unit positioned just below thereof may make an attachment
through the coating material on the outer surface of the second
separator.
[0047] For reference, when a coating material having adhesiveness
is coated on the separator, the direct pressurization onto the
separator by using an object is not recommended. Generally, the
separator is extended outwardly from the electrode. An attempt may
be made to combine the distal end portion of the first separator
112 and the distal end portion of the second separator 114 to each
other. For example, an attempt for welding the distal end portion
of the first separator 112 and the distal end portion of the second
separator 114 by means of sonication welding may be made. For the
sonication welding, a target is necessary to be directly
pressurized by using a horn. However, when the distal end portions
of the separators are directly pressurized by using the horn, the
horn may attach to the separator due to the coating material having
the adhesiveness. In this case, the apparatus may be broken.
Therefore, when the coating material having the adhesiveness is
coated on the separator, the direct application of the pressure
onto the separator by using an object is not preferable.
[0048] In addition, the radical unit 110 does not necessarily
include the four-layered structure. For example, the radical unit
110 may have an eight-layered structure formed by stacking the
first electrode 111, the first separator 112, the second electrode
113, the second separator 114, the first electrode 111, the first
separator 112, the second electrode 113 and the second separator
114 one by one . That is, the radical unit 110 may have a structure
formed by repeatedly stacking the four-layered structure. As
described above, the unit stack part 100 may be formed by
repeatedly stacking the radical units 110. Thus, the unit stack
part 100 may be formed by repeatedly stacking the four-layered
structure, or the unit stack part 100 may be formed by repeatedly
stacking, for example, the eight-layered structure.
[0049] Meanwhile, the unit stack part 100 may further include at
least one of a first auxiliary unit 130 and a second auxiliary unit
140. First, the first auxiliary unit 130 will be explained. The
radical unit 110 is formed by stacking the first electrode 111, the
first separator 112, the second electrode 113 and the second
separator 114 from the upper portion to the lower portion, or from
the lower portion to the upper portion, one by one . When the unit
stack part 100 is formed by repeatedly stacking the radical units
110, the first electrode 116 (Hereinafter, will be referred to as
`first distal end electrode`) may be positioned at the uppermost
portion (see FIG. 1), or at the lowermost portion (see FIG. 2) of
the unit stack part 100 (the first distal end electrode may be an
cathode or a anode.). The first auxiliary unit 130 may be
additionally stacked on the first distal end electrode 116.
[0050] More particularly, as illustrated in FIG. 4, when the first
electrode 111 is a cathode, and the second electrode 113 is an
anode, the first auxiliary unit 130a may be formed by stacking from
the first distal end electrode 116, that is, to the outer portion
from the first distal end electrode 116 (to the upper portion in
FIG. 4), the separator 114, the anode 113, the separator 112 and
the cathode 111 one by one. In addition, as illustrated in FIG. 5,
when the first electrode 111 is the anode, and the second electrode
113 is the cathode, the first auxiliary unit 130b may be formed by
stacking from the first distal end electrode 116, that is, to the
outer portion from the first distal end electrode 116, the
separator 114 and the cathode 113 one by one. As illustrated in
FIGS. 4 and 5, in the unit stack part 100, the cathode may be
positioned at the outermost portion of the first distal end
electrode 116 due to the first auxiliary unit 130.
[0051] Generally, an electrode includes a current collector and
active material layers (active material) coated on both sides of
the current collector. Thus, the active material layer positioned
under the current collector among the active material layers of the
cathode makes a reaction with the active material layer positioned
on the current collector among the active material layers of the
cathode in FIG. 4 through the separator. When the unit stack part
100 is formed by manufacturing the same radical units 110 and
stacking thereof one by one, the first distal end electrode
positioned at the uppermost portion or the lowermost portion of the
unit stack part 100 may include the active material layers on both
sides of the current collector as another first electrode. However,
when the first distal end electrode has a structure including the
active material layers coated on both sides of the current
collector, the active material layer positioned at the outer
portion among the active material layers of the first distal end
electrode may not make a reaction with another active material
layer. Thus, the wasting of the active material layer may be
generated.
[0052] The first auxiliary unit 130 is provided to solve the
above-mentioned defects. That is, the first auxiliary unit 130 is
separately formed from the radical units 110. Thus, the first
auxiliary unit 130 may include an cathode including the active
material layer formed only on one side of the current collector.
That is, the first auxiliary unit 130 may include an cathode
including the active material layer coated only on one side facing
the radical unit 110 (a side facing the lower portion in FIG. 4)
among both sides of the current collector. Consequently, when the
unit stack part 100 is formed by additionally stacking the first
auxiliary unit 130 on the first distal end electrode 116, the
cathode including the coated layer only on one outermost side of
the first distal end electrode 116 may be disposed. Thus, the
defects on the waste of the active material layer may be solved.
Since the cathode has a constitution releasing, for example, nickel
ions, the provision of the cathode at the outermost portion is
preferred when considering battery capacity.
[0053] Then, the second auxiliary unit 140 will be explained. The
second auxiliary unit 140 basically exhibits the same function as
the first auxiliary unit 130. More particularly, the radical unit
100 is formed by stacking the first electrode 111, the first
separator 112, the second electrode 113 and the second separator
114 from the upper portion to the lower portion, or from the lower
portion to the upper portion, one by one. When the unit stack part
100 is formed by repeatedly stacking the radical units 110, the
second separator 117 (Hereinafter, will be referred to as `second
distal end separator`) may be positioned at the uppermost portion
(see FIG. 2) or the lowermost portion (see FIG. 1) of the unit
stack part 100. The second auxiliary unit 140 may be additionally
stacked on the second distal end separator 117.
[0054] More particularly, as illustrated in FIG. 6, when the first
electrode 111 is an cathode, and the second electrode 113 is a
anode, the second auxiliary unit 140a may be formed as the cathode
111. In addition, as illustrated in FIG. 7, when the first
electrode 111 is a anode, and the second electrode 113 is an
cathode, the second auxiliary unit 140b may be formed by stacking
from the second distal end separator 117, that is, to the outer
portion of the second distal end separator 117 (to the lower
portion in FIG. 7), the anode 111, the separator 112 and the
cathode 113 one by one. The second auxiliary unit 140 may also
include an cathode including an active material layer coated only
one side facing the radical unit 110 (one side facing the upper
portion in FIG. 7) among both sides of the current collector as for
the first auxiliary unit 130. When the unit stack part 100 is
formed by additionally stacking the second auxiliary unit 140 on
the second distal end separator 117, an cathode including a coated
layer only on one side thereof may be positioned at the outermost
portion of the second distal end separator 117.
[0055] For reference, in FIGS. 4 & 5, and 6 & 7, stacked
structures of the first electrode 111, the first separator 112, the
second electrode 113 and the second separator 114 one by one, from
the upper portion to the lower portion, are illustrated. On the
contrary, stacked structures of the first electrode 111, the first
separator 112, the second electrode 113 and the second separator
114 one by one, from the lower portion to the upper portion, may be
explained by the same manner as described above. The first
auxiliary unit 130 and the second auxiliary unit 140 may further
include a separator at the outermost portion as occasion demands.
For example, when the cathode positioned at the outermost portion
is necessary to be electrically insulated from a case, the first
auxiliary unit 130 and the second auxiliary unit 140 may further
include a separator at the outermost portion of the cathode. For
such reasons, a separator may be further included in the cathode
exposed to the opposite side to the stacked portion of the second
auxiliary unit 140 (the uppermost portion of the electrode assembly
in FIG. 6).
[0056] Meanwhile, a unit stack part may be preferably manufactured
as illustrated in FIGS. 8 to 10. First, a unit stack part 100e as
illustrated in FIG. 8 may be formed. A radical unit 110b may be
formed by stacking a first electrode 111, a first separator 112, a
second electrode 113 and a second separator 114 from the lower
portion to the upper portion, one by one. In this case, the first
electrode 111 may be an cathode, and the second electrode 113 may
be a anode. A first auxiliary unit 130c may be formed by stacking
from the first distal electrode 116, that is, from the upper
portion to the lower portion as in FIG. 8, the separator 114, the
anode 113, the separator 112 and the cathode 111, one by one. In
this case, the cathode 111 of the first auxiliary unit 130c may
include an active material layer formed only on one side facing a
radical unit 110b.
[0057] In addition, a second auxiliary unit 140c may be formed by
stacking from a second distal end separator 117, and from the lower
portion to the upper portion in FIG. 8, an cathode 111 (a first
cathode), a separator 112, a anode 113, a separator 114 and an
cathode 118 (a second cathode), one by one. In this case, the
cathode 118 (the second cathode) positioned at the outermost
portion of the second auxiliary unit 140c may include an active
material layer formed only on one side facing the radical unit
110b. For reference, the alignment of the units may be easily
conducted when the auxiliary unit includes the separator.
[0058] Then, a unit stack part 100f as illustrated in FIG. 9 may be
formed. A radical unit 110b may be formed by stacking a first
electrode 111, a first separator 112, a second electrode 113 and a
second separator 114 one by one from the lower portion to the upper
portion. In this case, the first electrode 111 may be an cathode,
and the second electrode 113 may be a anode. A first auxiliary unit
130d may be formed by stacking the separator 114, the anode 113 and
the separator 112, one by one from a first distal end electrode
116. In this case, a second auxiliary unit may not be provided. For
reference, a anode may make a reaction with an aluminum layer of an
electrode case (for example, pouch) due to a potential difference.
Thus, the anode is preferably insulated from the electrode case by
means of the separator.
[0059] Finally, a unit stack part 100g as illustrated in FIG. 10
may be formed. A radical unit 110c may be formed by stacking a
first electrode 111, a first separator 112, a second electrode 113
and a second separator 114 from the upper portion to the lower
portion. In this case, the first electrode 111 may be a anode, and
the second electrode 113 may be an cathode. A second auxiliary unit
140d may be formed by stacking the anode 111, the separator 112,
the cathode 113, the separator 114 and the anode 119 one by one
from a second distal end separator 117. In this case, a first
auxiliary unit may not be provided.
[0060] Referring to FIG. 11, a fabricating method of an electrode
assembly according to the present invention will be explained.
[0061] In the fabricating method of an electrode assembly according
to the present invention, a step of forming a radical unit (S100)
for forming a radical unit 110 having a four-layered structure
formed by stacking a first electrode 111, a first separator 112, a
second electrode 113 and a second separator 114 one by one, and a
step of stacking the radical units for forming a unit stack part
100 (S200) by stacking at least one radical unit 110 one by one are
included. The explanation on the radical unit 110 and the unit
stack part 100 has been described above, and will be omitted.
[0062] The fabricating method of an electrode assembly according to
the present invention may further include a step of stacking a
first auxiliary unit (S300) in which a first auxiliary unit 130 is
stacked on a first distal end electrode 116, which is the first
electrode positioned at the uppermost portion or at the lowermost
portion of the unit stack part 100. In addition, the fabricating
method of the electrode assembly according to the present invention
may further include a step of stacking a second auxiliary unit
(S400) on a second distal end separator 117, which is the second
separator positioned at the uppermost portion or at the lowermost
portion of the unit stack part 100. The explanation on the first
auxiliary unit 130 and the second auxiliary unit 140 has been
described above, and will be omitted.
[0063] FIG. 12 illustrates an embodiment on using a fixing member
for fixing a unit stack part according to the present
invention.
[0064] A fabricating method of an electrode assembly according to
the present invention may further include a fixing step (S500)by
using a fixing part T1 for fixing the side portion or the front
portion of the unit stack part 100 including a stacked structure of
the radical units 110. That is, in order to confirm the stability
of a stacking structure, the unit stack part 100 may be fixed by
using a separate member at the side portion thereof. The fixing may
be accomplished by taping only the side portions of the unit stack
part 100 as illustrated in FIG. 12(a), or by using a fixing part T2
for fixing the whole sides of the unit stack part 100 as
illustrated in FIG. 12(b). In addition, a polymer tape may be used
as the fixing parts T1 and T2.
[0065] Hereinafter, particular materials and constitutional
features of constituent elements of the electrode assembly
according to the present invention will be explained.
[Cathode Structure]
[0066] In the present invention, an electrode provided in a radical
unit is classified into an cathode and a anode and is manufactured
by combining the cathode and the anode along with a separator
interposed therebetween. The cathode may be manufactured, for
example, by coating a slurry of a mixture of an cathode active
material, a conductive material and a binder on an cathode current
collector, drying and pressing. A filler may be added into the
mixture as occasion demands. When the cathode is accomplished as a
sheet shape to be installed on a roll, the manufacturing rate of
the radical unit may be increased.
[Cathode Current Collector]
[0067] An cathode current collector is generally manufactured to a
thickness of about 3 to 500 .mu.m. For the cathode current
collector, a material not inducing the chemical change of a battery
and having a high conductivity may be used without limitation. For
example, stainless steel, aluminum, nickel, titanium, clacined
carbon, a surface treated material of aluminum or stainless steel
with carbon, nickel, titanium, silver, or the like may be used. The
adhesiveness of an cathode active material may be increased by
forming minute embossing on the surface of the cathode current
collector. The cathode current collector may have various shapes
such as a film, a sheet, a foil, a net, a porous material, a foamed
material, a non-woven material, and the like.
[Cathode Active Material]
[0068] An cathode active material for a lithium secondary battery
may include, for example, a layered compound of lithium cobalt
oxide (LiCoO.sub.2), lithium nickel oxide (LiNiO.sub.2), etc. or a
substituted compound with one or more transition metals; lithium
manganese oxide such as Li.sub.1+xMn.sub.2-x,O.sub.4 (in which x is
0 to 0.33), LiMnO.sub.3, LiMn.sub.2O.sub.3, LiMnO.sub.2, etc.;
lithium copper oxide (Li.sub.2CuO.sub.2); vanadium oxide such as
LiV.sub.3O.sub.8, LiFe.sub.3O.sub.4, V.sub.2O.sub.5,
Cu.sub.2V.sub.2O.sub.7, etc.; Ni site-type lithium nickel oxide
represented by Chemical Formula of LiNi.sub.1-xM.sub.xO.sub.2 (in
which, M=Co, Mn, Al, Cu, Fe, Mg, B or Ga, x=0.01 to 0.3); lithium
manganese complex oxide represented by Chemical Formulae
LiMn.sub.2-xM.sub.xO.sub.2 (in which M=Co, Ni, Fe, Cr, Zn or Ta,
and x=0 .01 to 0.1) or Li Mn MO.sub.8 (in which, M=Fe, Co, Ni, Cu
or Zn) ; LiMn.sub.2O.sub.4 in which a portion of Li is substituted
with alkaline earth ions; a disulfide compound; Fe.sub.z
(MoO.sub.4).sub.3, and the like, without limitation.
[0069] Generally, a conductive material is added into a mixture
including the cathode active material by 1 to 50 wt % based on the
total amount of the mixture. Any conductive material having
conductivity without inducing the chemical change of a battery may
be used without limitation. For example, graphite such as natural
graphite, synthetic graphite, etc.; carbon black such as carbon
black, acetylene black, ketjen black, channel black, furnace black,
lamp black, thermal black, etc.; conductive fiber such as carbon
fiber, metal fiber, etc.; a metal powder such as a carbon fluoride
powder, an aluminum powder, a nickel powder, etc.; conductive
whisker such as potassium titanate, etc.; conductive metal oxide
such as titanium oxide, etc.; a conductive material such as
polyphenylene derivatives, etc. may be used
[0070] A binder is a component assisting the bonding of the active
material with the conductive material and the bonding with the
current collector, and is commonly included by about 1 to 50 wt %
based on the total amount of the mixture including the cathode
active material. Examples of the binder may include polyfluoro
vinylidene, polyvinyl alcohol, carboxymethyl cellulose (CMC),
starch, hydroxypropyl cellulose, regenerated cellulose, polyvinyl
pyrrolidone, tetrafluoroethylene, polyethylene, polypropylene,
ethylene-propylene-diene polymer (EPDM), sulfonated EPDM, styrene
butadiene rubber, fluorine rubber, various copolymers, etc.
[0071] A filler is a component restraining the expansion of the
cathode and is selectively used. A material not inducing the
chemical change of a battery and having a fiber phase may be used
without limitation. For example, olefin-based polymer such as
polyethylene, polypropylene, and the like; fiber phase material
such as glass fiber, carbon fiber, and the like may be used.
[Anode Structure]
[0072] A anode may be manufactured by coating a anode active
material on a anode current collector, drying and pressing. A
conductive material, a binder, a filler, etc. may be selectively
included as occasion demands. When the anode is formed as a sheet
shape to be installed on a roll, the manufacturing rate of a
radical unit may be increased.
[Anode current Collector]
[0073] A anode current collector is generally manufactured to a
thickness of about 3 to 500 .mu.m. For the anode current collector,
a material not inducing the chemical change of a battery and having
conductivity may be used without limitation. For example, copper,
stainless steel, aluminum, nickel, titanium, clacined carbon, a
surface treated material of copper or stainless steel with carbon,
nickel, titanium, silver, an aluminum-cadmium alloy, etc. may be
used. Also, as for the cathode current collector, the adhesiveness
of the anode active material may be increased by forming minute
embossing on the surface of the anode current collector. The anode
current collector may have various shapes such as a film, a sheet,
a foil, a net, a porous material, a foamed material, a non-woven
material, etc.
[Anode Active Material]
[0074] A anode active material may include, for example, carbon
such as non-graphitizable carbon, graphite-based carbon, etc.; a
metal complex oxide such as Li.sub.xFe.sub.2O.sub.3
(0.ltoreq.x.ltoreq.1), Li.sub.xWO.sub.2 (0.ltoreq.x.ltoreq.1),
Sn.sub.xMe.sub.1-xMe'.sub.yO.sub.z, (Me: Mn, Fe, Pb, Ge; Me': Al,
B, P, Si, elements found in Group 1, Group 2 and Group 3 in a
periodic table, halogen; 0<x<1; 1.ltoreq.y.ltoreq.3;
1.ltoreq.z.ltoreq.8), etc.; a lithium metal; a lithium alloy; a
silicon-based alloy; a tin-based alloy; a metal oxide such as SnO,
SnO.sub.2, PbO, PbO.sub.2, Pb.sub.2O.sub.3, Pb.sub.3O.sub.4,
Sb.sub.2O.sub.3, Sb.sub.2O.sub.4, Sb.sup.2O.sub.5, GeO, GeO.sub.2,
Bi.sub.2O.sub.3, Bi.sub.2O.sub.4, Bi.sub.2O.sub.5, etc .; a
conductive polymer such as polyacetylene, etc.; Li--Co--Ni-based
material, etc.
[Separator]
[0075] A separator according to the present invention forms a
radical unit through conducting a simple stacking process apart
from a folding process or a roll process to accomplish the simple
stacking. Particularly, the attachment of the separator, with the
cathode and the anode may be accomplished by melting a separator
sheet itself by heat to accomplish attaching and fixing in a
laminator. From the above-described process, a pressure is
continuously maintained and a stable interface contact between the
electrode and the separator sheet may become possible.
[0076] Any material that may exhibit insulating properties and have
a porous structure for the movement of ions may be used for the
manufacture of the separator sheet or the separator interposed
between the cathode and the anode of a cell. The separator and the
separator sheet may include the same material or not.
[0077] For the separator or the separator sheet, for example, an
insulating thin film having a high ion transmittance and mechanical
strength may be used. The pore diameter of the separator or the
separator sheet is commonly about 0.01 to 10 .mu.m, and the
thickness thereof is commonly about 5 to 300 .mu.m. As for the
separator or the separator sheet, for example, an olefin-based
polymer such as chemical-resistant and hydrophobic polypropylene,
etc.; a sheet or a non-woven fabric obtained by using glass fiber,
polyethylene, or the like, may be used. When a solid electrolyte
such as a polymer is used as an electrolyte, the solid electrolyte
may also function as the separator. Preferably, a polyethylene
film, a polypropylene film, or a multi-layered film obtained by
combining the films, or a polymer film for a polymer electrolyte or
a gel-type polymer electrolyte such as polyvinylidene fluoride,
polyethylene oxide, polyacrylonitrile, or polyvinylidene fluoride
hexafluoropropylene copolymer, may be used.
[0078] The electrode assembly according to the present invention
may be applied in an electrochemical cell producing electricity
through the electrochemical reaction of a cathode and a anode.
Typical examples of the electrochemical cell include a super
capacitor, an ultra capacitor, a secondary battery, a fuel cell,
all sorts of sensors, an apparatus for electrolysis, an
electrochemical reactor, and the like. The secondary battery is
particularly preferred.
[0079] Secondary battery has a structure in which a
chargeable/dischargeable electrode assembly having an impregnated
state with an ion-containing electrolyte is built in a battery
case. In a preferred embodiment, the secondary battery may be a
lithium secondary battery.
[0080] Recently, a lithium secondary battery attracts much concern
as a power source of a large size device as well as a small size
mobile device. A light weight lithium secondary battery may be
preferred for applying thereof in these fields. As one method of
decreasing the weight of the secondary battery, a built-in
structure including an electrode assembly in a pouch-type case of
an aluminum laminate sheet may be used. Since the features on the
lithium secondary battery are well known in this art, the
explanation on the lithium secondary battery will be omitted.
[0081] In addition, as described above, when the lithium secondary
battery is used as the power source of a medium and large size
device, a secondary battery maximally restraining the deterioration
of an operating performance for a long time, having good lifetime
properties and having a structure possibly being mass-produced with
a lower cost, may be preferred. From this point of view, the
secondary battery including the electrode assembly of the present
invention may be preferably used as a unit battery in a medium and
large size battery module.
[0082] A battery pack including a battery module including a
plurality of secondary batteries may be used as a power source in
at least one medium and large size device selected from the group
consisting of a power tool; an electric vehicle selected from the
group consisting of an electric vehicle (EV), a hybrid electric
vehicle (HEV), and a plug-in hybrid electric vehicle (PHEV); an
E-bike; an E-scooter; an electric golf cart; an electric truck; and
an electric commercial vehicle.
[0083] The medium and large size battery module is constituted of a
plurality of unit batteries connected in a serial system or a
serial/parallel system so as to provide a high output and high
capacity. The techniques on these features are well known in this
art. Thus, the explanation on the features will be omitted in this
application.
[0084] While the present invention has been shown and described in
connection with the exemplary embodiments, it will be apparent to
those skilled in the art that modifications and variations can be
made without departing from the spirit and scope of the invention
as defined by the appended claims.
* * * * *